ARCHAEOLOGICAL, SOIL AND MICROBIOLOGICAL STUDIES OF THE MOSKVA RIVER FLOODPLAIN DEPOSITS AT THE ZVENIGOROD BIOLOGICAL PLANT

В статье приводятся результаты применения методов почвенно-микробиологического исследования культурных слоев в пойменных отложениях Москвы-реки. Выявлена корреляция пиков численности сапротрофных и термофильных бактерий с горизонтами погребенных почв в толще аллювия, к которым приурочены археологические находки. Показано, что с помощью микробиологических анализов можно выявить следы хозяйственной активности, которая датируется ранним бронзовым веком. The paper describes results of soil and microbiological studies of the occupation layers in the Moskva River floodplain deposits. The study identified a correlation between peaks in the count of the saprotrophic and thermophilic bacteria with the horizons of buried soils in the stream sediments where archaeological finds were made. The paper shows that micro bioassays can help identify traces of economic activity dating to the early Bronze Age.

Age and Palynological Characteristics of Floodplain Deposits of the Kolyma Lowland (North-East Siberia)

River floodplains, reaching several kilometers in width, are one of the main landscape features of the Kolyma Lowland. Their relationship with other forms of relief - yedoma, alasses, and fragments of river terraces - is seen clearly in the Bolshaya Kuropatoch'ya River basin, which is located in the Lowland between 156°30' E and 157°15' E. The first radiocarbon dating of the floodplain deposits of the Kolyma Lowland was undertaken in a study of an outcrop on the left bank of the Bolshaya Kuropatoch'ya River (71°40' N, 156°45' E). Here floodplain sediments, represented by the alternating layers of alluvial silt and peat with a total thickness of 5 m, were exposed along a steep bank of an oxbow lake. The radiocarbon results show that the formation of the modern floodplain of the Bolshaya Kuropatoch'ya River began at the end of the Middle Holocene and continued during the Late Holocene to the present. Since the vegetation cover of arctic and subarctic regions is characterized by low pollen productivity, the spore-pollen spectra of modern and fossil plant communities often include an increased amount of pollen from plant species exotic to the Arctic, brought to the site by long-distance wind transport. For a more reliable interpretation of the spore- pollen spectra of the floodplain sediments, an analysis of the modern vegetation in the Bolshaya Kuropatoch'ya River basin and in a coastal area bordering the East Siberian Sea (about 71°05' N) was carried out, accompanied by an herbarium collection. The radiocarbon-dated palynological data indicate the development of the modern Betula-Salix shrub-herbaceous tundra during the second half of the Holocene. The establishment of this vegetation community reflects the replacement of an earlier Betula forest-tundra, which had prevailed in the northern regions of Western Beringia during the Early Holocene and included Duschekia fruticosa and large shrub species of Salix. Such dramatic changes in the vegetation cover were associated with the rise in sea level about 7.000-6.000 years ago, when seas approached modern levels. This change, in turn, led to a decrease in the contrast of summer and winter temperatures and, thus, to a decrease in the continentality of the climate and a significant reduction in the growing season in the coastal regions of the East Siberian Sea.

Karakteristik Kawasan Pesisir Pantai Cilamaya (Teluk Blanakan dan Teluk Ciasem), Kabupaten Subang, Propinsi Jawa Barat

Kawasan pesisir utara Pulau Jawa merupakan kawasan yang sering mengalami perubahan akibat proses hidrometeorologi termasuk pesisir Cilamaya. Paling tidak ada 4 sungai yang mengalir bermuara antara lain Citarum (lama), Blanakan, Cilamaya dan Ciasem. Secara geomorfologi relatif datar yang tersusun dari proses proses fluvial dan proses asal laut sebagai endapan dataran banjir, endapan alur sungai, endapan estuari dan endapan laut. Endapan limpah banjir tersusun oleh lempung lanauan dan lempung kadang dijumpai adanya kerakal dan brangkal, dimanfaatkan oleh masyarakat sebagai Sawah, tanaman padi. Pasir, karekal dan berangkal merupakan material penyusun endapan alur sungai. Estuari terdiri dari material organik dan lempung. Daerah ini tertutup oleh hutan mangrove dan tambak. Endapan laut didominasi endapan yang berukuran halus lempung dan pasir (halus – kasar) dengan dibeberapa tempat kadang dijumpai pecahan cangkang.Kata kunci: Cilamaya, Kawasan Pesisir, estuariCoastal area in the northern of Java island is part of the always changes caused by hidrometeorogy aspect include the Cilamaya costal area. At least there are four river flow are (old) Citarum, Blanakan, Cilamaya and Ci Asem river. Geomorphologically the relief ralatively flat from the fluvial and marine proccesses, as floodplain, river (channel), estuaries (wet land), marine deposits. The floodplain deposits consists of silty clay and clay some time with pebble, use for the paddy field and some urban area. Sand, pebble and coble are from the river (channel). Estuary consists of organic material and clay, very weak. In the estuary cover by mangrove forest and fish pond. The marine deposits dominantly clay and sand (fine to coarse) with some place found broken shell. The hazards relation with the condition should be mitigate are subsidance, flood from the river and tide (rob).Keyword: Cilamaya, coastal area, estuaries

Erratum: V.I. Roslikova, L.A. Matyushkina, “Differentiation of the soil cover of the floodplain of the Middle-Amur Lowland in connection with the evolution of the relief forms”

Dear readers, on page 111 in Volume 106 of Dokuchaev Soil Bulletin, 2021, (2021;(106):105-129) the caption to figure 1:“Fig. 1. Scheme of the structure of floodplain deposits of the Amur River within the Middle-Amur Lowland, formed over a long period of time under the conditions of directed sediment accumulation. Deposits of facies: 1 – channel sand (sand with gravel); 2 – levee (fine sand); 3 – floodplain (sandy loam and loam); 4 – old riverbed (loam with silty interlayers); 5 – eolian riolkas (relatively high fine sand ridges) (Sokhina, 1973)”should read:“Fig. 1. Scheme of the structure of floodplain deposits of the Amur River within the Middle-Amur Lowland, formed over a long period of time under the conditions of directed sediment accumulation. Deposits of facies: 1 – channel sand (sand with gravel); 2 – levee (fine sand); 3 – floodplain (sandy loam and loam); 4 – old riverbed (loam with silty interlayers); 5 – eolian riolkas (relatively high fine sand ridges) (Makhinov, 2006)”.

The importance of overbank deposits and paleosol analyses for comprehensive volcanic hazard evaluation: The case of Holocene volcanism at Miravalles Volcano, Costa Rica

On the flanks of the dormant Miravalles volcano, systematic fieldwork and radiocarbon dating of buried humus-rich soils (paleosols) and wood fragments, augmented by mineralogical and geochemical analysis, reveal extensive and previously undocumented Holocene activity. Phase 1 consisted of 8.3 ka (~6300 BCE) volcanic debris avalanche and thick lapilli blast and fallout deposit that appear coeval. Hiatus 1 marks 2600 years of inactivity ensued followed by Phase 2 lapilli interbedded with ~5.5 ka lahars below a 5.3 ka basaltic lava flow (~3400 BCE). Hiatus 2 lasted 1800 years from 5.3 ka to 3.5 ka (3300-1500 BCE), after which a very active Phase 3 ensued (3.5 to 0.5 ka; 1600 BCE to 1500 CE) with > four lapilli eruptions, > 4 lahars, > 6 layers of ash and pumice, and small andesitic lava flows. The most recent evidence for eruption is an 880-year-old (0.9 ka; 1070 CE) lapilli overlain by gravels that may represent distal lahar sediments. Evidence indicates the occurrence of at least two, if not three, destructive lahars on the southwest flank of Miravalles in the past 500 years. The overbank sedimentary record indicates much more activity of Miravalles volcano over the past 3500 years (since 1500 BCE) than previously known, with a minimum of 24 events in that span. Overbank floodplain deposits are likely to contain the most compete record of recent activity in active and dormant volcanoes, and in the absence of dateable vegetation fragments, radiocarbon dating of paleosol A-horizons is very useful, with a precision of ~ 10%, i.e. 800 + 80 ybp.

Testing hypotheses on signatures of precipitation variability in the river and floodplain deposits of the Paleogene San Juan Basin, New Mexico, U.S.A.

ABSTRACTMuch progress has been made in recent years towards a set of recognition criteria for river discharge variability in river channel deposits, and thus sedimentary proxies for precipitation variability. Despite this progress, there is currently no consensus on how different styles of discharge variability are reflected in river sedimentary records, and whether variable-discharge river records from different climate types can be distinguished. Herein, river discharge and precipitation variability in the Paleogene is investigated using associations between river channel and floodplain deposits across the Paleocene–Eocene boundary from the Paleocene upper Nacimiento Formation and the early Eocene San Jose Formation in the San Juan Basin, New Mexico, USA.The succession is identified as deposits of variable-discharge river systems based on shared channel-deposit characteristics with modern and ancient variable-discharge river systems and the proposed facies models, in addition to alternations of poorly drained and well-drained floodplain deposits and/or slickensides indicating alternating wet–dry cycles. A long-term stratigraphic trend toward increasingly well-drained floodplain deposits is also observed and hypothesized to indicate successively more arid conditions from the Paleocene into the early Eocene. Comparisons with modern rivers from various climate zones suggest a long-term shift from a monsoonal climate in the Paleocene, to a fluctuating subhumid climate, ultimately leading to semiarid to arid conditions in the early Eocene. These observations suggest that floodplain deposits may be a better indicator of ambient climate, whereas channel deposits are records for frequency and magnitude of high-intensity precipitation events. Therefore, the existing facies models for variable-discharge rivers that consider only channel facies may not capture critical information needed to make accurate interpretations of paleoclimatic conditions. This study also adds to a growing body of evidence from geologic records of mid-latitude Paleogene river systems suggesting increases in the magnitude or variability of river discharge coinciding with established climate perturbations.

Facies architecture and time stratigraphic relationships of a confined trunk-tributary valley fill and unconfined fluvial system in the backwater of the Turonian Ferron-Notom Delta, Utah, U.S.A.

ABSTRACT This paper documents a tidally incised, mudstone-prone tributary valley fill linked to a trunk valley in the backwater limit of the Turonian Notom Delta of the Ferron Sandstone Member, Utah. High-resolution 3D photogrammetry models were used to correlate a 20-m-deep valley between 32 measured sections over a 1 km2 area. A GPS survey and GIS geostatistical tools were used to restore the morphology of the tributary valley. The restored valley floor is interpreted as a surface of tidal erosion, based on the overlying facies and surface morphology. Morphological similarities exist between this tributary valley and modern analogs observed in northern Australia, the Memramcook tributary in the Bay of Fundy, and Pleistocene sediments in the Gulf of Thailand. 40Ar/39Ar dating of sanidine crystals using multi-collector mass spectrometry allow for a re-evaluation of depositional rates and timing of 32 fluvial aggradation cycles (FACs) and 9 fluvial-aggradation cycle sets (FAC sets) in this sequence. The new dates show that the entire sequence was deposited in 15 ± 5 kyr, and show that Milankovitch cycles cannot account for the internal complexity of this fluvial stratigraphy, indicating likely autogenic control of the FAC sets. The lateral extent of FACs in floodplain deposits mapped in outcrop are correlated over tens to hundreds of meters, and scale to estimated channel widths reflecting the autogenic control. FAC sets can be correlated for up to 10 km along depositional strike, which suggest controls unrelated to the dynamics of individual channels and may show some elements of allogenic climate-driven processes.

Diverse floodplain deposits of reworked loess in a monsoon climate (Hanzhong Basin, central China)

This paper describes an assemblage of diverse floodplain facies of reworked loess (facies b, c) in a Middle Pleistocene monsoonal setting of the Hanzhong Basin, central China. The vertical and lateral sedimentary sequences show changing energy conditions. Apart from the highest energy in the channel facies (facies a), a relatively high energy floodplain environment (facies b) prevailed in waterlogged conditions, with small, laterally migrating (sub)channels. Facies b generally interfingers with aggrading horizontal sheets of overbank deposits in alluvial pools and swamps in a floodplain with much lower energy (facies c), in which phases of stability (soil formation) occasionally interrupted overbank deposition. Reworked loess forms the main part of the floodplain deposits. The paleosols are considered to have been formed under low hydrodynamic conditions in an interglacial environment. These interglacial conditions follow the commonly assumed glacial conditions of channel facies a. The sedimentary successions in the floodplain show a recurrent composition and cyclicity between wet and dry floodplain sedimentation terminated by stability with soil formation. The cyclic rhythm of stacked high- and low-energy floodplain sediments is attributed to varied intensity of different hydrodynamic flooding events that may have been due to changing monsoonal rainfall or simple intrinsic fluvial behavior.

Seismically Induced Soil Liquefaction and Geological Conditions in the City of Jama due to the M7.8 Pedernales Earthquake in 2016, NW Ecuador

Seismically induced soil liquefaction has been documented after the M7.8, 2016 Pedernales earthquake. In the city of Jama, the acceleration recorded by soil amplification yielded 1.05 g with an intensity of VIII to IXESI-07. The current study combines geological, geophysical, and geotechnical data in order to establish a geological characterization of the subsoil of the city of Jama in the Manabi province of Ecuador. Then, the liquefaction potential index (LPI) has been evaluated considering the PGA-rock values calculated from deterministic methods applied to nearby geological faults, as well as the soil acceleration records for the city of Jama since the Pedernales megathrust earthquake. The importance of conducting geotechnical evaluations of particular colluvial, alluvial, and floodplain deposits, for which the liquefaction probability profiles have been additionally obtained, may serve as a useful tool for edifices foundations or earthquake resistant designs. Finally, the site response analysis is presented using a linear equivalent analysis, where previously seismic records compatible with the target spectrum have been selected. Hereby, the results of ground surface effects have been compared with the spectra of the Ecuadorian Regulation of Construction (NEC) in the context of local seismic amplification.